启动第二个Activity

activity_main.xml文件：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    >

   <Button
       android:id="@+id/myButton"
       android:layout_width="wrap_content"
       android:layout_height="wrap_content"
       android:text="启动第二个Activilty"
       />


</RelativeLayout>

创建activity_second.xml文件：

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
    android:layout_height="match_parent" android:paddingLeft="@dimen/activity_horizontal_margin"
    android:paddingRight="@dimen/activity_horizontal_margin"
    android:paddingTop="@dimen/activity_vertical_margin"
    android:paddingBottom="@dimen/activity_vertical_margin"
    tools:context="com.example.z1178.test.SecondActivity">



    <TextView
        android:id="@+id/secondView"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="第二个Activity"
        />

</RelativeLayout>

SecondActivity.java:

package com.example.z1178.test;

import android.os.Bundle;
import android.support.v7.app.ActionBarActivity;


public class SecondActivity extends ActionBarActivity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_second);
    }
}

MainActivity.java文件：

package com.example.z1178.test;

import android.app.Activity;
import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;


public class MainActivity extends Activity {

    private static final String TAG="debug";
    private Button myButton;




    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        myButton=(Button)findViewById(R.id.myButton);
        buttonClickListener listener=new buttonClickListener();

        myButton.setOnClickListener(listener);


    }


    class  buttonClickListener implements View.OnClickListener{

        @Override
        public void onClick(View v) {
            Intent intent=new Intent();
            //setClass的第一个参数为Context对象（Activity为其子类），第二个参数为要启动的Activity
            intent.setClass(MainActivity.this,SecondActivity.class);
            startActivity(intent);
        }
    }
}

AndroidManifest.xml文件：

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.example.z1178.test" >

    <application
        android:allowBackup="true"
        android:icon="@mipmap/ic_launcher"
        android:label="@string/app_name"
        android:theme="@style/AppTheme" >
        <activity
            android:name=".MainActivity"
            android:label="@string/app_name" >
            <intent-filter>
                <action android:name="android.intent.action.MAIN" />

                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
        </activity>
        <activity
            android:name=".SecondActivity"
            android:label="@string/title_activity_second" >
        </activity>
    </application>

</manifest>

对于back stack，其维护的Activity对象，我们需要注意的是，其总是显示顶端的Activity，当我们按回退键的时候，back stack会按照与进去栈的相反顺序依次显示对应的Activity。